The flow of fluids, typically water, or air, or cement grout or resin, is commonly pumped through hollow tubes, hollow drill rods, hollow rock bolts and hollow self drilling rock bolts in the mining and tunneling industries. Most commonly water or air is used to flush rock cuttings out of boreholes as they are being drilled by hollow drill rods. Also cement grout or resin is commonly pumped through the central hole in hollow injection rods to stabilise broken, fractured or weak rock or ground. In addition, cement grout or resin is also commonly pumped through hollow rock bolts or hollow self drilling rock bolts to anchor those rock bolts into rock or soil. An example of a hollow self drilling rock bolt with a drilling tip at one end is given in patent number PCT/AU91/00503.
The hollow drill rods or hollow rock bolts may be made from any suitable hollow bar including tubes, pipes or thick-walled hollow bars, and are typically made from steel but could be made from fibreglass or plastic or carbon fibre.
Where fluids are pumped through a hollow bar for any of the above applications, a sealing means is normally used between the hollow bar and the fluid pumping system. Typically, where drilling applications using drill rods are being used, the fluid pumping system is through the drilling machine using either water or air.
This sealing means can be as simple as a screw thread on the end of the hollow bar or hollow drill rod or hollow rock bolt which is screwed into a mating thread inside the drill chuck on the drilling machine. Alternatively this sealing means is typically an O ring either on the end of the hollow bar, or inside the drill chuck. The O ring prevents leakage of the fluids as they are being pumped through the hollow bar, and they are a simple, low cost and proven method of sealing fluids for this application.
In some applications two fluids are pumped through a hollow bar at the same time for drilling applications. Typically this may be water and air such that a fine “mist” is used for drilling to minimise the volume of water used. Alternatively, two fluids may be pumped through a hollow bar at different times, for example, water may be used for drilling cycle to flush rock cuttings out of the borehole, and then cement grout may be subsequently pumped through the same hollow bar to fill the borehole with cement grout and anchor the hollow bar into the borehole.
In the civil and tunneling industries this operation is typically undertaken by firstly screwing the end of a hollow bar or hollow drill rod or hollow rock bolt with a thread on the end of it into a drill chuck, and then rotating the bar during the drilling cycle. The rotational action of the drilling machine tightens the mating threads between the bar and the drill chuck and creates a seal for the fluids used for the drilling cycle. Once the drilling cycle is complete, the bar is unscrewed form the drill chuck and a screw fitting attached to a grout hose is typically screwed onto the end of the bar. This screw fitting is typically manually tightened up onto the end of the bar such that a fluid seal is created which then allows cement grout or resin or other chemical anchoring fluid to be pumped into and through the bar to fill the borehole. Once the borehole is full of the cement grout or other anchoring fluid, then the screw fitting is unscrewed from the bar and removed.
The use of screw threads or O rings are therefore the most common forms of sealing for pumping fluids through hollow bars, hollow drill rods or hollow rock bolts in the mining, civil and tunneling industries.
The screwing and unscrewing of screw threads is a cumbersome operation and where cement grout hoses and fittings are used, it is typically undertaken manually. This is a time consuming operation and is not suited to automation of the grouting process.
In addition, the use of either screw threads or O Rings for sealing of fluids being pumped through hollow bars is principally designed for sealing against leakage at the seal itself, and they are not designed to direct and control the flow of fluids either inside the drill chuck or inside the hollow bar.
In the particular case of self drilling rock bolts, water, or air, or water and air, known as the “drilling fluid” are typically pumped through the bolt to remove the rock cuttings from the drilling operation to drill a borehole. An example of a self drilling rock bolt is given in patent number PCT/AU2006/001775. A sealing device is used to prevent leakage of the drilling fluid between the drilling machine and the bolt. Once the borehole has been drilled, and all the rock cuttings have been removed from the borehole, pumping of the drilling fluid is then turned off. Then cement grout, or resin, or other chemical fluid, known as the anchoring fluid, is typically pumped through the bolt to fill the borehole and fully encapsulate the bolt in the borehole and once the anchoring fluid cures and hardens, it anchors and fixes the bolt in the borehole. Typically with current systems, the drilling fluid and the anchoring fluid are pumped into self drilling rock bolts through separate hoses and fittings which have to be separately attached and detached from the end of the self drilling rock bolt, and typically this is done manually.
Moreover, if a two part chemical resin is pumped into a hollow bar, or into a hollow bolt or into a hollow self drilling rock bolt, then the two part chemical resin normally consists of a hardenable component (known as a mastic component) and a hardening component (known as a catalyst component). Typically once the mastic component comes into contact with the catalyst component the resin will start to cure, and it may harden in less than 60 seconds, typically it will harden in less than 30 seconds. Clearly then the mastic component must be kept completely separate from the catalyst component, while these two components of the resin are being pumped through the drilling machine and through the drilling chuck of the drilling machine, otherwise it will cure and harden and clog the drilling chuck. In addition, if an injection nozzle is used in the drilling chuck to inject the two part resin into the hollow bolt, then the two parts of the chemical resin, the mastic component and the catalyst component, must also be kept separate immediately after or above the injection nozzle, otherwise premature curing can occur and cause blockages of this injection nozzle.
Furthermore if the pumping pressures within the mastic component and the catalyst component as they flow out of the injection nozzle are unequal, then it is possible to get backflow of either mastic or catalyst down the wrong passageway, and this can cause blockages within the injection nozzle. An injector for use with self drilling rock bolt which does not have a one way valving and passageway system as described this invention, is prone to blockages and an example of such an injector is given in patent number AU199959340 A1.
More particularly where an injection nozzle is used to pump one or more fluids into a hollow bar either simultaneously or sequentially, there is a considerable advantage in being able to use that one injection nozzle to pump one or more fluids into the hollow bar without the requirement to screw or unscrew different fittings onto the end of the bar to pump different fluids into the bar. However, the resin injection system as shown in patent number AU199959340 A1 is prone to blockages. The inventor has found that if the mastic part of a liquid resin and the catalyst part of a liquid resin are allowed to come together immediately at the end of an injector, then the end of the injector is likely to become clogged with resin that has cured and hardened. To prevent the injector becoming clogged with hardened resin it is necessary to keep the mastic part of the resin and the catalyst part of the resin completely separate as they leave the injector and force them to flow along their own separate passageways inside the end of the bolt. The mastic and catalyst then flow along their own separate passageways inside the bolt, and only come together and mix at some point further away from the end of the injector. In practice the distance between the end of the injector and the point where the mastic and catalyst come together and mix may be small and typically be between 5 mm and 50 mm but is not so limited.
Moreover, the inventor has further found that where two or more fluids are being pumped into a hollow bar either simultaneously or sequentially, it is often necessary to prevent back flow of one or more fluids in the wrong direction down a passageway used for another fluid, and or it is often necessary to prevent premature mixing of two or more fluids. Moreover, if two or more fluids are being pumped into a hollow bar simultaneously, the pumping pressures for each fluid may not be equal and this could cause back flow or flow through the wrong passageway. Therefore it is necessary to have a one way valving system that will prevent back flow of liquid resins along the wrong passageway, and typically this can be achieved by having separate one way valves along each passageway inside the bolt.
Furthermore, if separate passageways and one way valves are only used in the injector, clogging of the end of the injector by curing and hardening of two part liquid resins is still possible. For example patent number WO2006042530 shows an injection head with two separate passageways with two separate valves which then combine into a single passageway in a connecting piece which is then inserted into the end of a hollow bar or bolt. However this patent indicates that this single passageway in the connecting piece has to be flushed out after use, otherwise the two part liquid resins will cure and harden in the passageway entering the bolt making the injector unusable for subsequent bolts.
There is therefore a considerable advantage in having an injection, sealing, passageway and valving system for used with hollow self drilling rock bolts that enables:                drilling rotation of the bolt;        water or air flushing of the drill cuttings;        injection of a liquid resin mastic component and injection of a liquid resin catalyst component into and through the bolt to fill the borehole;        mixing, curing and hardening of the two liquid resin components to anchor the bolt in the borehole;        tensioning of a nut on the end of the hollow self drilling rock bolt;        removal of the injector from the hollow self drilling rock bolt;and all be accomplished without back flow of resin along the wrong passageway in the injector, or contamination or clogging of any part of the injector, and leaving the injector completely clean after it is removed from the bolt and be ready to install the next hollow self drilling rock bolt.        
Even further, there is a considerable advantage in being able to maintain a hydraulic seal or seals between a stationary injector with one or more passageways and a rotating bolt in which the injector is inserted into or is coupled to.
The present invention relates to an injection, sealing, passageway and valving means which overcomes the problems of existing systems described above and allows one or more fluids to be simultaneously or sequentially pumped into and through a hollow bar, a hollow drill rod or hollow rock bolt, without back flow or contamination and enabling the resin in the bolt to cure and harden without clogging the injector, and also leaving the injector completely clean after it is removed from the bolt and be ready to install the next bolt.
There is a need for improved mechanism or device to overcome the above problems of manually changing over separate hoses and fittings to pump different fluids into hollow bars, and to control and direct the flow of those fluids inside the hollow bar. Moreover there is a need to have separate passageways with optional one way valves to control the flow of chemical resins to prevent back flow, flow along the wrong passageway and avoid premature mixing and curing of chemical resins, grouts or other anchoring fluids.
The present inventor has developed an injection, sealing, valving and passageway system that can be installed substantially in the end of a hollow bar or a hollow drill rod or a hollow rock bolt or hollow self drilling rock bolt and or partially within an external injector that overcomes these problems and enables one or more fluids to be pumped into and through a hollow bar or hollow drill rod or hollow bolt or hollow self drilling rock bolt without premature mixing or back flow or leakage such that these bars, rods or bolts can be installed with a minimum of manual handling and without blockage of the injector or the dill chuck.
Furthermore the injection, sealing, valving and passageway system enables water to be pumped through a hollow self drilling rock bolt during the drilling operation while the bolt is being rotated, and then enables resin or cement grout to be pumped through the bolt during the grouting cycle, without any change to the sealing or valving system. The injection, sealing, valving and passageway system can not only function and hydraulically seal while a hollow self drilling rock bolt is being rotated at drilling speeds of typically 500 rpm, but it can also hydraulically seal and separate two part resins, chemicals or grouts during the grouting cycle. This has the considerable advantage that there is no requirement to change over fittings on the end of the bolt between the drilling cycle and the grouting cycle as occurs with current practice.